Continuous motion robotic manipulator

ABSTRACT

A continuous motion robotic device including a first robotic arm, a second robotic arm, a third robotic arm, and a drive system. The robotic arms are coaxially arranged, each including an end effector for performing useful work on an object and can continuously rotate a full 360. The drive system commonly controls the three robotic arms and defines a central axis about which the device rotates. The device is capable of high-speed operation in that the robotic arms are sequentially presented to various work environment stations via rotation about the central axis. In one preferred embodiment, each of the robotic arms provides three degrees of freedom. In another preferred embodiment, each robotic arm includes at least a first primary joint and a second primary joint, with the first primary joints being coupled and the second primary joints being coupled. Alternatively, the primary joints are decoupled.

BACKGROUND OF THE INVENTION

The present invention relates to a robotics-based, automatedobject-handling device. More particularly, it relates to a continuousmotion device incorporating multiple, coaxially arranged robotic arms.

Automated object handling equipment is utilized in countless industrialapplications. For example, automated processing equipment is useful forproduct or component construction, assembly, packaging, inspection, etc.In this regard, automated processing equipment can assume a wide varietyof forms, but are generally categorized in one of two distinct classes.The first class of automated processing equipment is high-speeddedicated machinery characterized by continuous motion mechanisms, suchas a rotating turntable, that allows the machinery to operate smoothlyat high speeds. A second class, generally referred to as robotics,utilizes a reciprocating, computer controlled robotic arm to performcertain operations. Both classes of automated machinery have certainadvantages and drawbacks. For example, dedicated machinery is typicallyless complex, and is able to process a much larger volume of componentsthrough various stations as compared to robotic machinery due to thecontinuous motion design. Conversely, robotic machinery is typicallyable to perform more complex motions, and can more readily bereconfigured or programmed for different work environments/handlingrequirements.

Efforts have been made to improve upon the effective speeds of roboticmachinery. For example, U.S. Pat. No. 5,042,774 describes coaxiallymounting two robotic arms. While providing enhanced operationalcapabilities, the arms are not capable of rotating 360°, and thereforecannot provide a more preferred, continuous motion. Conversely, otherreferences, such as U.S. Pat. Nos. 5,678,980, 5,789,878, and 6,102,164describe a semiconductor wafer-transferring device including twocommonly linked robotic arms secured to a central hub. Whileeffectuating a continuous motion feature, the so-described robotic armsare limited to two degrees of freedom, and operate in different planes.As a result, while satisfying specific constraints associated withsemiconductor wafer processing, the described robotic assemblies haveminimal usefulness for other manufacturing scenarios. Further, only twoarticles can be handled at any one time. Other continuous motion roboticarm designs are similarly limiting.

A multitude of design obstacles have contributed to the inability toperfect a continuous motion, multiple robotic arm system. First, it isnot enough to simply stack two or more robotic arms on top of oneanother. In addition to the obvious complications associated withdriving such a system, the arms are manipulated out-of-plane relative toone another, thereby limiting the potential manufacturing applications.Second, to optimize overall efficiency, it is greatly preferred thatmore than two robotic arms be provided with a single device. Once again,this constraint has heretofore presented insurmountable obstacles indevising an appropriate, and cost-effective, drive system. Third, forenhanced arm manipulation, it is preferred that each robotic arm beprovided with three degrees of freedom. While single arm, three degreeof freedom robots are well known, existing drive systems for theserobotic devices are not amenable to a continuous motion, multi-armdevice. Fourth, the availability of desired arms paths by coupling oruncoupling the various arms lengths has not been explored. Fifth, thesystem is preferably highly flexible. That is to say, an optimalcontinuous motion robotic system affords the user the ability to quicklyand easily alter a portion of the system such that the resulting armpaths satisfy the requirements of different handling applications. Theseconstraints in combination with industry's willingness to accept thedrawbacks associated with dedicated machinery and robotic devices, havelikely hindered design efforts into a continuous motion robotic handlingdevice.

Material handling systems or machinery continue to evolve.Unfortunately, however, a system optimally combining the attributes ofhigh-speed dedicated machinery and flexible or robotic machinery iscurrently unavailable. Therefore, a need exists for a continuous motionrobotic device providing multiple robotic arms that is useful for a widevariety of different processing applications.

SUMMARY OF THE INVENTION

One aspect of the present invention relates to a continuous motionrobotic device for processing objects. The system includes a firstrobotic arm, a second robotic arm, a third robotic arm, and a drivesystem. Each of the robotic arms includes an end effector for performinguseful work on an object. Further, the robotic arms are coaxiallyarranged relative to one another. Finally, the drive system commonlycontrols the three robotic arms and defines a central axis about whichthe device rotates. With this configuration, the system is capable ofhigh-speed operation in that the robotic arms are sequentially presentedto various work environment stations via rotation about the centralaxis. Further, by commonly controlling the three robotic arms with thedrive system, the robotic arms are optimally sized while affordingconsistent, controlled paths for each of the end effectors. In onepreferred embodiment, each of the robotic arms is comprised of threeprimary links and three primary joints, thereby providing three degreesof freedom. In another preferred embodiment, each robotic arm includesat least a first primary joint and a second primary joint, with thefirst primary joints being coupled to one another and the second primaryjoints being coupled to one another. Alternatively, in another preferredembodiment, the primary joints are decoupled.

Another aspect of the present invention relates to a continuous motionrobotic device for processing objects. The device includes a pluralityof robotic arms and a drive system. Each of the plurality of roboticarms includes a first primary link, a first primary joint, a secondprimary link, a second primary joint, and an end effector. The firstprimary links are rotatable about the respective first primary joints.The second primary joint connects the second primary link to the firstprimary link. Finally, the end effector is provided to perform work onan object. With this construction in mind, each of the first primarylinks are continuously rotatable about a common axis via the base.Further, each of the first primary joints are coupled to one another,and each of the second primary joints are coupled to one another.Finally, the drive system controls the robotic arms. In particular, thedrive system includes a first input and a second input. The first inputcommonly drives the first primary joints, whereas the second inputcommonly drives the second primary joints. With this configuration,then, a continuous motion robotic system is provided in which each ofthe robotic arms has at least two degrees of freedom. Further, bycoupling the first and second primary links, the end effectors aredriven to trace the same path at the same time.

Yet another aspect of the present invention relates to a method ofprocessing objects within a workspace. The method includes providing acontinuous motion robotic device including three coaxially arrangedrobotic arms. Each of the arms has an end effector and extends radiallyfrom a hub defined by a drive system. Further, the drive system commonlydrives the three robotic arms. Based upon the parameters of a firstworkspace, a first desired path for the end effectors is determined. Thedrive system is then configured to articulate the end effectors throughthe first desired path. The robotic device is positioned within thefirst workspace. Finally, the drive system is operated such that the endeffectors pass through the first desired path to process objects withinthe first workspace. In one preferred embodiment, the method furtherincludes determining a second desired path for the end effectors basedupon parameters of a second workspace. The drive system is reconfiguredso as to articulate the end effectors through the second desired path.The robotic device is positioned within the second workspace. Finally,the drive system is operated such that the end effectors pass throughthe second desired path to process objects within the second workspace.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a simplified, top view of a continuous motion robotic devicein accordance with the present invention incorporating coupled roboticarms;

FIG. 1B is a simplified, top view of an alternative embodimentcontinuous motion robotic device in accordance with the presentinvention incorporating decoupled robotic arms;

FIG. 1C is a simplified, top view of a continuous motion robotic devicein accordance with the present invention incorporating robotic arms withsliding joints;

FIG. 2 is a perspective view of a first embodiment, continuous motionrobotic device in accordance with the present invention includingcoupled robotic arms;

FIG. 3 is a perspective view of a mechanical-based drive mechanism forthe device of FIG. 2;

FIG. 4A is a top view of a second embodiment, continuous motion roboticdevice in accordance with the present invention including coupledrobotic arms;

FIG. 4B is a simplified, side-sectional view of the device of FIG. 4A;

FIG. 5A is a top view of a third embodiment, continuous motion roboticdevice in accordance with the present invention including decoupledrobotic arms;

FIG. 5B is a top view of a fourth embodiment, continuous motion roboticdevice;

FIG. 5C is a top view of a fifth embodiment, continuous motion roboticdevice;

FIG. 6A is an enlarged perspective view of a portion of a drive systemuseful with the devices of FIGS. 5A–5C;

FIG. 6B is an enlarged, bottom view of a portion of the drive system ofFIG. 6A;

FIG. 7A is an enlarged perspective view of a portion of an alternativedrive system useful with the devices of FIGS. 5A–5C;

FIG. 7B is a cross-sectional view of a portion of FIG. 7A;

FIG. 7C is an enlarged, schematic illustration of a portion of the drivesystem of FIG. 7A;

FIG. 8A is a top view of a mechanical-based drive system useful with thedevices of FIGS. 5A–5C;

FIG. 8B is a bottom view of a portion of the drive system of FIG. 8A;

FIG. 9A is a top view of a sixth embodiment, continuous motion roboticdevice in accordance with the present invention including decoupledrobotic arms;

FIG. 9B is a side, perspective view of the device of FIG. 9A;

FIG. 9C is a side, schematic illustration of the device of FIG. 9A;

FIG. 10A is a perspective view of a portion of a cam-based drive systemfor the device of FIG. 10B;

FIG. 10B is a perspective view of the device of FIG. 9A incorporatingthe drive system of FIG. 10A; and

FIGS. 11A and 11B are simplified, block diagrams illustrating use of acontinuous motion robotic device in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a continuous motion robotic device inwhich multiple, coaxially arranged robotic arms are commonly driventhrough a full 360 degrees of motion by a drive system. In this regard,and with respect to various preferred embodiments described below, therobotic arms can be coupled or decoupled relative to one another. Withthis in mind, FIG. 1A illustrates a coupled arrangement, whereas FIG. 1Brelates to a decoupled configuration. In particular, FIG. 1A depicts, inhighly simplified form, one preferred embodiment of a continuous motionrobotic device 20. The device 20 includes a plurality of robotic arms 22a–22 d and a drive system 24 (shown in block form). In the embodiment ofFIG. 1A, each of the robotic arms 22 a–22 d are provided with threedegrees of freedom and include a first primary link 26, a second primarylink 28, and a third primary link 30. The third primary link 30terminates in, or is connected to, an end effector 32 (shown generallyin FIG. 1A). The end effector 32 is configured to perform work on anobject (not shown). Regardless, the robotic arms 22 a–22 d arepreferably identically constructed, and are rotatably connected to abase 34 by a first primary joint 36. Further, for each individual arm 22a–22 d, the second primary link 28 is pivotably connected to the firstprimary link 26 by a second primary joint 38. Similarly, the thirdprimary link 30 is pivotably connected to the second primary link 28 bya third primary joint 40. While the primary joints 36–40 have beenillustrated as being rotary joints, other configurations are equallyacceptable. For example, as described in greater detail below, one ormore of the primary joints 36–40 can be sliding joints.

While each of the robotic arms 22 a–22 d has been illustrated asincluding three of the primary links 26–30, and thus three degrees offreedom, in an alternative embodiment, only two of the primary links areincluded such that robotic arms 22 a–22 d have two degrees of freedom.Conversely, four or more primary links can be provided for each of thearms 22 a–22 d. Even further, the additional link(s) and related jointscan be fashioned to provide movement in the z-direction (i.e., intoand/or out of the page of FIG. 1A).

The first primary links 26, and in particular the first primary joints36, are rigidly coupled to one another by a hub 42 otherwise rotatablydriven by the drive system 24. As described in greater detail below, thedrive system 24 either rotatably drives the hub 42, or causes the firstlinks 26 to rotate about the hub 42 at the first primary joints 36. Witheither arrangement, the first primary links 26, via the first primaryjoints 36, rotate about a center point of the hub 42, such that therobotic arms 22 a–22 d are coaxially aligned. Further, although notspecifically illustrated in FIG. 1A, each of the second primary joints38, and thus each of the second primary links 28, are connected orcoupled to one another via the drive system 24. The third primary joints40, and thus the third links 30, are also connected or coupled to oneanother by the drive system 24. As a result, the robotic arms 22 a–22 d,and in particular the respective primary joints 36–40, are characterizedas being “coupled” to one another, whereby a “coupled joint” is inreference to the associated primary links sweeping the same angle duringthe same period in time.

Specific primary joint coupling techniques are provided below. Ingeneral terms, the respective primary joints 36–40 are directlyconnected to a coupling device; or the associated primary links 26–30are directly connected to a coupling device, resulting in a “coupling”of the corresponding primary joints 36–40. Regardless of exact form,however, the rigidly connected first primary joints 36 are commonlydriven by a single input (not shown) defined by the drive system 24.Similarly, the second primary joints 38 and the third primary joints 40are also commonly driven by second and third inputs (not shown),respectively, defined by the drive system 24. With this configuration,then, the end effectors 32 are transmitted through, or trace, thesubstantially same path (designated as “P” in FIG. 1A) at the same time.As a result, the end effectors 32 are positioned at a substantiallyidentical radial distance relative to a center point of the hub 46.Preferably, the paths and radial positions of the end effectors 32 areidentical. However, expected machining tolerances, joint clearances andcontrol system errors/deviations can slightly alter the paths andpositions. As such, some minor fluctuation in path and radial position(relative to identical paths and position) is expected. Regardless, thespeed of the end effectors 32 are preferably prescribed along the path,and as such can increase, decrease or even stop (dwell) for a briefperiod.

Notably, while the device 20 has been illustrated in FIG. 1A asincluding four of the robotic arms 22 a–22 d, any other number isequally acceptable. Regardless of the number of robotic arms 22 a–22 d,only three inputs are required of the drive system 24 for driving therobotic arms 22 a–22 d each having three degrees of freedom.

The device 20 has been described with reference to coupled robotic arms22 a–22 d. Alternatively, the robotic arms 22 a–22 d need not be coupledas described above, but instead can be essentially “decoupled”. Moreparticularly, FIG. 1B illustrates, in simplified form, an alternativeembodiment, continuous motion robotic device 50. The device 50 includesidentically constructed robotic arms 52 a–52 d and a drive system 54(shown in block form). Each of the robotic arms 52 a–52 d are providedwith three degrees of freedom, and thus include a first primary link 56,a second primary link 58, and a third primary link 60. The third primarylink 60 terminates in, or is connected to, an end effector 62 configuredto perform work on an object (not shown). Each of the first primarylinks 56 are connected to a base 64 at a first primary joint 66.Further, for each of the arms 52 a–52 d, the second primary link 58 isconnected, preferably rotatably connected, to the first primary link 56by a second primary joint 68; and a third primary joint 70 connects,preferably rotatably connects, the third primary link 60 to the secondprimary link 58. Once again, more or less than four of the robotic arms52 a–52 d can be provided, and each arm 52 a–52 d can have more or lessthan three degrees of freedom.

As described in specific embodiments below, the drive system 54 includesthree inputs that commonly drive each of the primary links 56–60,respectively. In this regard, the drive system 54 rotates the firstprimary links 56 about a common center point (via the first primaryjoints 66) such that the arms 52 a–52 d are coaxially aligned. Incontrast to the device 20 (FIG. 1A), however, the respective primarylinks 56–60 and the primary joints 66–70 for each of the arms 52 a–52 dare essentially decoupled from one another. With this configuration,each of the end effectors 62 traces substantially the same path(designated as “P′” in FIG. 1B), but the arms 52 a–52 d do not do thesame thing at the same point in time. In other words, each of therobotic arms 52 a–52 d generates substantially the same motion atsubstantially the same point of the path P′. In other words, the roboticarms 52 a–52 d are directed through substantially identical paths(relative to inherent machining tolerances, joint clearance and controlsystem error factors), and the respective end effectors 62 arepositioned at different radial distances relative to a center pointduring at least one period in time. Thus, the robotic arms 52 a–52 d areevenly distributed in time, but not in space. As a result, the roboticarms 52 a–52 d may then get closer or farther from each other duringrotation thereof depending upon the particular path P′. Notably, thedecoupled path P′ can be chosen to vary over a complete 360 degreerotation. In contrast, the coupled path P (FIG. 1A) can only be chosenfor 360/n where n, equals the number of robotic arms. Further, ascompared to the coupled path P, the decoupled path P′ can be chosen withno redundant motions and will generally be much smoother and faster thanthe coupled path P. Finally, similar to the coupled path P, thedecoupled path P′ can prescribe the speed of the end effectors 62 atevery point such that the end effectors 62 can travel faster, slower, oreven stop (dwell) for some time at any spatial point.

The various primary joints associated with the devices 20, 50 have beenillustrated as being rotary joints. Alternatively, as FIG. 1C depicts,in simplified form, a continuous motion robotic device 72 having aplurality of robotic arms 73 each incorporating a sliding joint. Moreparticularly, each of the arms 73 includes a first primary link 74(shown generally, but integrally formed as part of a hub), a secondprimary link 75, and a third primary link 76. The first primary links 74rotate about a first primary joint 77. The second primary joints 78 aresliding joints. Finally, the third primary links 76 are rotatablyconnected to respective ones of the second primary links 75 by a thirdprimary joint 79. Alternatively or in addition, the third primary joints79 can be sliding joints. Even further, one or more of the joints 77,78, 79 can be prismatic joints.

As described below, the inventive continuous motion robotic devices 20,50 can be effectuated with a variety of different drive systemconfigurations. In this regard, two basic constructions of the drivesystem 24, 54 are available. In one preferred embodiment, the drivesystem 24, 54 is servo-motor based. Servo-motors are well known in theart and can be implemented as described. Alternatively, the drive system24, 54 can be mechanical in nature. More particularly, the drive system24, 54 can include one or more specifically designed cam mechanisms.With this in mind, each of the following alternative embodiments arefirst described without reference to a specific drive system technique,it being understood, however, that a drive system of some type must beincluded and will either be servo-motor based or mechanically based.Also, it should be noted that in each of the following embodiments, thenumber of robotic arms, and the degrees of freedom provided for eacharm, are merely exemplary. Finally, in each of the various embodiments,as well as in the descriptions of FIGS. 1A and 1B, reference to “endeffectors” is made in general terms. As will be apparent to one ofordinary skill, “end effectors” can assume a wide variety of formscapable of performing some type of work on an object. For example, theend effectors can be vacuum suction cups, mechanical grippers, sprayheads, etc. With any one type of end effector, it will be understoodthat additional components, mechanisms, etc., may be required, but arenot shown.

A first preferred embodiment of a coupled continuous motion roboticdevice 80 is shown in FIG. 2. The device 80 includes a plurality ofrobotic arms 82 and a drive system 83 a portion of which is illustratedas having a first input 84, second input 86, and a third input 88. Tobetter illustrate various components, portions of the robotic arms 82 aand 82 b have been removed from the view of FIG. 2. With this in mind,each of the robotic arms 82 includes a first primary link 90 (showngenerally as a portion of the first input 84), a second primary link 92,and a third primary link 94. Each of the third primary links 94 servesas an end effector (shown generally in FIG. 2). With this configuration,each of the robotic arms 82 is provided with three degrees of freedom.

Each of the first primary links 90 effectively is formed by a hub 96otherwise defined by the first input 84. As described below, the hub 96is rotatable about a central axis A, such that a common, coupled firstjoint 100 is defined for each of the first primary links 90. To betterillustrate the first primary links 90, FIG. 2 includes phantom linesdesignating individual, imaginary links formed along the hub 96, itbeing understood that the hub 96 is, in reality, a continuous structurethat rigidly forms the first primary links 90. Each of the secondprimary links 92 is rotatably connected to a respective one of the firstprimary links 90 by a second primary joint 102. Similarly, each of thethird primary links 94 is rotatably connected to a respective one of thesecond primary links 92 by a third primary joint 104.

As previously described, the first input 84 forms the hub 96 to whichthe first primary links 90 are rigidly formed or otherwise connected.Similarly, the second input 86 forms a master gear 112 that couples, andthus commonly drives motion of, each of the second primary joints 102,and thus each of the second primary links 92. In this regard,interaction between the master gear 112 and the secondary primary joints102 can be frictional, or the respective components 92, 112 can beformed to include interlocking teeth, such as by a plurality of smallgears 110 that are otherwise rigidly attached to a respective secondprimary link 92. Finally, in one preferred embodiment, a plurality ofpulley belts 114 are provided, respective ones of which extend through acentral portion of one of the second primary links 92, and are connectedto one of the third primary joints 104, respectively. Further, the thirdinput 88 forms a hub or gear 116 that commonly engages each of thepulley belts 114, such as by a plurality of small gear 118 that areotherwise rigidly attached to a respective pulley belt 114. Thus, thethird input 88, via the gears 116, couples the third primary joints 104,and thus, commonly drives the third primary links 94.

Each of the robotic arms 82, and in particular the first primary joints100, are coaxially positioned about the central axis A. Further, each ofthe inputs 84–88 rotate about the central axis A. To this end, theinputs 84–88 include a coaxially-arranged shafts 120–124, respectively.With this configuration, each of the first primary joints 100 arecoupled to one another by the first input 84, and in particular the hub116. Similarly, each of the second primary joints 102 are coupled to oneanother via the second input 86, and in particular the master gear 112.Finally, each of the third primary joints 104 are coupled to one anotherby the third input 88, and in particular the gear 116. Thus, rotation ofthe first input 84 causes each of the first primary links 90, via thefirst primary joints 100, to rotate in an identical fashion. Similarly,rotation of the second input 86 drives each of the second primary links92, via the second primary joints 102, through an identical motion.Finally, rotation of the third input 88 drives each of the third primarylinks 94, via the third primary joints 104, through an identical motionvia the pulley belts 114.

The drive system 83 requires only three of the inputs 84–88 to drive allof the robotic arms 82 (each having three degrees of freedom). In onepreferred embodiment, the drive system 83 is comprised of threeservo-motors driving respective ones of the shafts 120–124.Alternatively, the drive system can incorporate a cam-basedconfiguration, one example of which is shown in FIG. 3. In particular,FIG. 3 illustrates the second input 86 and a barrel cam 130. The secondinput 86 includes a plate 131 and a plurality of circumferentiallyspaced followers 132. As a point of reference, the plate 131 is securedto the shaft 122 opposite the master gear 112 (FIG. 2). The followers132 are sized to fit within, and be driven by, a cam path or slot 134formed in an exterior of the barrel cam 130. Thus, rotation of thebarrel cam 130, such as by a motor (not shown), causes the plate 131 torotate about the central axis A via interaction of the followers 132within the cam path 134. This rotation is translated to the master gear112 via the shaft 122, and applied to the second primary joints 102(FIG. 2) via the gears 110 (FIG. 2). Notably, additional barrel cams andplates are provided for each of the first input 84 and the third input88, respectively. The various cam paths 134 formed by the three barrelcams 130 can be identical or different, and can assume a wide variety ofconfigurations (or axial spacings). Further, one or more of the campaths 134 can approximate a dwell for the respective input 84–88.

An alternative embodiment coupled continuous motion robotic device 150is shown in FIGS. 4A and 4B. In general terms, the device 150 includes aplurality of robotic arms 152 and a drive system 153 a portion of whichis shown including a first input 154, a second input 156, and a thirdinput 158. Each of the robotic arms 152 is preferably provided withthree degrees of freedom and includes a first primary link 160, a secondprimary link 162, and a third primary link 164, with the third primarylink 164 terminating in, or forming, an end effector 166. As with thedevice 80 (FIG. 2) previously described, each of the first primary links160 are integrally formed as part of the first input 154, and thereforedo not exist as visually discernable parts (in the preferredembodiment). To better illustrate the first primary links 160, however,phantom lines have been drawn into the relevant portion of the firstinput 154 to provide a visual representation of the components 160. Withthis in mind, each of the first primary links 160 are coupled to thefirst input 154 at a first primary joint 168. As described below, thefirst input 154 is rotatable, such that the first primary joints 168 arerotary joints, and are rigidly coupled to one another. Each of the firstprimary links 160 are connected to respective ones of the second primarylinks 162 by a second primary joint 170, respectively. Finally, for eachrobotic arm 152, the second primary link 162 is rotatably connected tothe third primary link by a third primary joint 172, respectively. Thus,in one preferred embodiment, each of the robotic arms 152 has threedegrees of freedom.

Each of the robotic arms 152, and in particular the first primary joints168, are coaxially positioned relative to one another, and are rotatableabout a common axis B, via the first input 154. In this regard, and asbest shown in FIG. 4B, the first input 154 includes a drive hub 180 anda central shaft 182. The drive hub 180 of the first input 154 integrallyforms or defines each of the first primary links 160, and rigidlycouples each of the first primary joints 168. Similarly, the secondinput 156 includes a drive hub 184 and a central shaft 186. The drivehub 184 of the second input 156 is connected, and rotatably drives, eachof the second primary joints 170. In one preferred embodiment, a firstextension arm 188 and a first secondary link 190 are provided for eachof the robotic arms 152, connecting the drive hub 184 to the secondprimary joint 170, respectively. The first extension arm 188 is formedas a rigid extension of the drive hub 184, whereas the first secondarylink 190 connects the first extension arm 188 and the second primarylink 162. Finally, the third input 158 includes a drive hub 192 and acentral shaft 194. The drive hub 192 is connected to, and rotatablydrives, each of the third primary joints 172. In this regard, a secondextension arm 196 and a second secondary link 198 are, in one preferredembodiment, provided for each of the robotic arms 152, connecting thedrive hub 192 to the third primary joint 172, respectively. The secondextension arm 196 is formed as a rigid extension of the drive hub 192,whereas the second secondary link 198 is connected to the secondextension arm 196 and the third primary link 164. Thus, the drive hub192 drives the third primary joints 172 via the second extension arm196, the second secondary link 198, and the third primary link 164.Finally, as shown in FIG. 4B, the central shafts 182, 186, and 194 arecoaxially arranged (similar to the device 80 of FIG. 2). With thisconfiguration, regardless of the exact number of robotic arms 152, onlythree inputs 154–158 are required, yet each of the arms 152 is providedwith three degrees of freedom.

Once again, the first input 154, and in particular the drive hub 180,rigidly couples the first primary joints 168. Thus, the first input 154commonly drives movement of each of the first primary joints 168 and thefirst primary links 160. The second input 156, and in particular thedrive hub 184, couples each of the second primary joints 170 via therespective first and second secondary links 188, 190. Notably, otherconnection designs are available for connecting the second primaryjoints 170 to the drive hub 184. Regardless, the second input 156commonly drives movement of each of the second primary joints 170 andthe second primary links 162. Finally, the third input 158, and inparticular the drive hub 192, couples each of the third primary joints172 via the respective third and fourth secondary links 196, 198.Notably, other connection techniques for connecting the third primaryjoints 172 to the drive hub 192 are equally acceptable. Regardless, thethird input 158 commonly drives movement of each of the third primaryjoints 172 and the third primary links 164.

In addition to the inputs 154–158, the drive system 153 associated withthe device 150 can assume a variety of forms. In one preferredembodiment, the drive system 153 further includes three servo-motors, asknown in the art, rotatably driving the central shafts 182, 186, 194,respectively. Alternatively, the drive system can be cam-based,utilizing three barrel cams; one for each of the inputs 154–158,respectively. In this regard, the cam-based configuration can be similarto that shown in FIG. 3.

The above-described continuous motion robotic devices 80 and 150inherently couple respective links or joints of the various roboticarms. Alternatively, the robotic arms can be decoupled. An example ofsuch a device is shown generally at 200 in FIG. 5A. The device 200includes a plurality of robotic arms 202 and a closed loop track 204. Asdescribed in greater detail below, the track 204 serves as one or moreinputs of a drive system (shown generally in FIG. 5A) for driving therobotic arms 202. Regardless, each of the robotic arms includes a firstprimary link 206, a second primary link 208, and a third primary link210 forming or maintaining an end effector 211. In the embodiment ofFIG. 5A, the first primary link 206 is a cart secured to, and moveablealong, the track 204. Thus, each of the first primary links 206 arerotatable about a center point defined by the track 204. Effectively,then, each of the first primary links 206 are connected to the drivesystem 205 by a first primary joint 212 otherwise defined at an instantcenter of the track 204. To better illustrate a relationship between thefirst primary links 206 and the respective first primary joints 212, anextension of two of the first primary links 206 is shown in phantom inFIG. 5A. Once again, the phantom lines associated with exemplary firstprimary link 206, as well as the first primary joints 212, do notphysically exist; instead they are represented in FIG. 5 to betterillustrate the rotational point of each of the first primary links 206.The second primary links 208 are rotatably connected to the firstprimary links 206 by second primary joints 214, respectively. Finally,the third primary links 210 are rotatably connected to the secondprimary links 208 by third primary joints 216, respectively.

The track 204 is preferably circular, defining a single centerpoint.Alternatively, however, the track 204 can assume a wide variety of othershapes. Where the track 204 is something other than circular, the track204 effectively defines a plurality of instant centers (relative to alocation of a particular cart at a specific point in time). Thus, for anon-circular track, a number of different center points (or point ofrotation for the first primary links 206) exist. The particular centerpoint depends on the location of the cart and thus the specific instantcenter being encountered.

The track 204 includes an inner guide 220 and an outer guide 222 (showngenerally in FIG. 5A). At least the first primary links or carts 206 aremoveably nested between the inner and outer guides 220, 222. Varioustechniques for driving the first primary links or carts 206, as well asother components and alternative embodiments are provided below. Ingeneral terms, however, each of the first primary links or carts 206 ismoveable about the path defined by the track 204. With thisconfiguration, then, the track 204 serves as a first input for the firstprimary links or carts 206. The drive system 205 further provides asecond input 224 for each of the second primary joints 214. While thesecond inputs 224 can be configured to drive movement of each of thesecond primary joints 214, thus, the second primary links 208, in anidentical fashion, the second primary joints 214 are not coupled to oneanother by the second inputs 224. That is to say, the second inputs 224are independently drivable such that use of the second primary joints214, and thus each of the second primary links 208, are passed throughdifferent angles at the same point in time. Similarly, the drive system205 provides a third input 226 for each of the third primary joints 216.As with the second inputs 224, the third inputs 226 are independent ofone another such that the third primary joints 216, and thus the thirdprimary links 210, are not coupled to one another.

In the one embodiment of FIG. 5A, each of the second and third inputs224, 226 are servo-motors driving the respective second and thirdprimary joints 214, 216. This configuration provides optimal flexibilityof motion and is kinematically simple, such that the drive system 205 iseasy to program and control. Alternatively, and as shown in FIG. 5B,each of the robotic arms 202 can be provided with a pulley belt 230extending from the third primary joint 216 within the second primarylink 208. With this embodiment, the servo-motors serving as the thirdinputs 226 are moved inwardly from the third primary joints 216, yetcontrol movement thereof via the respective pulley belts 230. Thus, thepotential cantilever concerns presented by a placement of a servo-motoron the third primary links 210 is alleviated. In fact, the servo-motorcould be moved to the opposite side of the second primary joint 214 toassist in counter balancing the mass of the respective end effector 211.

Alternatively, the second and third inputs 224, 226, need not beservo-motors, but instead can be formed as part of the drive systemprovided by the track 204. In this regard, FIG. 5C illustrates analternative continuous motion decoupled robotic device 240. As a pointof reference, FIG. 5C illustrates only one of the robotic arms 202 and aschematic illustration of the track 204. Once again, the robotic arm 202includes the first primary link or cart 206, the second primary link208, the third primary link 210, the first primary joint 212, the secondprimary joint 214, and the third primary joint 216. The first primarylink 206 serves as the first input to the first primary joint 212 viathe track 204. In addition, the device 240 includes a second input 242and a third input 244. The second input 242 includes a drive cart 246and a coupler link 248. The drive cart 246 is moveably coupled to, anddrivable about, the track 204 as described in greater detail below. Thecoupler link 248 is rotatably connected to the drive cart 246 by a firstsecondary joint 250; and rotatably coupled to the second primary link208 by a second secondary joint 252. Thus, the drive cart 246 drives thesecond primary joint 214 via the coupler link 248 and the second primarylink 208.

The third input 244 includes a drive cart 258, a drive link 260, and acoupler link 262. The drive cart 258 is moveably mounted to the circulartrack 204 as described below. The drive link 260 is rigidly attached to,and extends from, the drive cart 258. The coupler link 262 is rotatablyconnected to the drive link 260 by a first secondary joint 264; and thethird primary link 210 by a second secondary joint 266. With thisconfiguration, movement of the drive cart 258 is translated to the thirdprimary joint 216 via the drive link 260, the coupler link 262 and thethird primary link 210.

Though not shown, additional, similarly-constructed arms 202 and inputsare connected to the track 204. During use, the carts 206, 246, 258associated with each arm 202 are articulated about the circular track204 in a desired fashion. The carts 206, 246, 258 can be movedidentically or differently, such that an arc length spacing between eachof the carts 206, 246, 258 can vary during a full 360-degree rotation ofthe respective robotic arm 202. With this configuration, then, the drivesystem 205 dictates a desired spatial position and orientation of theend effector 213. Notably, with the embodiment of FIGS. 5A–5C, each ofthe robotic arms 202, and in particular the end effectors 213, arecoplanar.

The embodiments illustrated in FIGS. 5A–5C are but three examples ofacceptable configurations of the robotic arms 202 relative to the track204. That is to say, other secondary connecting approaches are equallyacceptable. Regardless of the exact design, however, at least one cart(such as the first primary link 206) is moveably mounted to, anddrivable about, the track 204. One preferred mounting and drivingtechnique is illustrated schematically in FIGS. 6A and 6B. As a point ofreference, FIG. 6A depicts a portion of the circular track 204 and aportion of one of the robotic arms 202. FIG. 6B depicts an enlargedportion of the track 204 and the cart of one arm 202. Once again, thetrack 204 includes the inner guide 220 and the outer guide 222. Thefirst primary link or cart 206 is nested between the inner and outerguides 220, 222. Further, a stationary gear 270 (shown generally inFIGS. 6A and 6B) extends radially outwardly relative to the inner guide220. Further, the first primary link or cart 206 is provided with adrive gear 272 and a servomotor 274 (shown schematically). The gears270, 272 are formed with intermeshing teeth (not shown), with theservo-motor 274 dictating rotation of the drive gear 272. The outerguide 222 constrains the first primary link or cart 206 such that thestationary gear 272 does not disengage the stationary gear 270. Withthis configuration, then, activation of the servo-motor 274 causes thedrive gear 272 to rotate against the stationary gear 270. This action,in combination with the constraining force presented by the outer guide222 causes the first primary link or cart 206 to move about the track204. Notably, this configuration can be provided for only the firstprimary link or cart 206 (such as in FIGS. 5A and 5B), or for threedifferent carts per each robotic arm (such as with the configuration ofFIG. 5C).

An alternative approach for mounting and driving one or more carts aboutthe track 204 is illustrated in FIGS. 7A–7C. In general terms, theembodiment of FIGS. 7A–7C entails use of a linear motor to drive therespective parts (such as the first primary link or cart 206) about thecurved track 204. With this in mind, FIG. 7A illustrates a portion ofthe track 204, a tooling cart 280 and a magnet system 292. The track 204includes the inner guide 220 and the outer guide 222. The tooling cart280 (analogous to the first primary link or cart 206 of FIG. 5A) isnested between, and drivable about, the inner and outer guides 220, 222.Finally, the magnet system 292 is positioned below the tooling cart 280.

With further reference to FIG. 7B, the cart 280 is connected to a linearmotor 282 and further includes opposing inner wheels 284, opposing outerwheels 286, and, in one preferred embodiment, an encoder sensor 287. Theinner guide 220 forms guide surfaces 288 configured to receive theopposing inner wheels 284. Similarly, the outer guide 222 forms surfaces290 configured to receive the opposing outer wheels 286. Further, themagnet system 292 extends between the inner and outer guides 220, 222,and is configured to drive the linear motor 282, as described in greaterdetail below. Finally, an encoder scale 294 extends in a circularfashion adjacent the inner guide 220, and is configured to interact withthe encoder sensor 287 associated with the cart 280. Although notillustrated in the various figures, it will be understood thatappropriate electrical connections and controllers are provided for eachof the linear motors 282, the encoder sensor 287, the magnet system 292,and the encoder scale 294. With this configuration, then, the linearmotor 282 is driven, via the magnet system 292 about the circular track204 with the inner and outer wheels 284, 286 riding along the respectivesurfaces 288, 290.

FIG. 7C provides an enlarged, top view of a portion of the magnet system292. In general terms, the magnet system 292 is comprised of a pluralityof magnets 300 arranged in an arc-like fashion. FIG. 7C furtherillustrates coils 302 a, 302 b associated with the linear motor 282 ofFIGS. 7A and 7B. Current direction within each of the coils 302 a, 302 bis illustrated with arrows. The magnetic flux direction alternates fromup to down with alternate magnets 300 (as shown in FIG. 7C). In apreferred embodiment, each of the magnets 300 are wedge-shaped, having aslightly greater width adjacent the outer guide 222 (as compared to awidth adjacent the inner guide 220). With this one preferredconfiguration, then, uniform gaps 304 are defined between adjacentmagnets 300. Current flowing through the coils 302 a, 302 b cuts throughthe magnetic field generated by the permanent magnets 300, providing aforce on the energized coil 302 a, 302 b. By controlling the directionand strength of the current in the coils 302 a, 302 b, the force on thecoils 302 a, 302 b via the magnetic field can be controlled, thuscontrolling movement of the cart 280. The encoder sensor 287 providesfeedback information regarding a position of the cart 280 relative tothe circular track 204 via interaction with the encoder scale 294. Thisfeedback allows accurate commutation, or reversing, of the current, aswell as position, velocity and acceleration feedback for the controlsystem.

In another alterative embodiment, the drive system 205 associated withthe device 200 of FIGS. 5A–5C is mechanically-based. For example, FIGS.8A and 8B illustrate a drive system 320 useful with the device 240 ofFIG. 5C. As a point of reference, FIG. 8A schematically illustrates thetrack 204 and the carts 206, 246, 258 for driving one of the roboticarms 202 (FIG. 5C). For ease of illustration, the various other links208, 210, 248, 260, 262, (FIG. 5C) have been omitted from the view ofFIG. 8A. It will be recognized that each additional robotic arm 202 willinclude an identical set of three carts 206, 246, 258 pursuant to theembodiment of FIG. 5C. Alternatively, with respect to the embodiment ofFIGS. 5A and 5B, each of the carts 206, 246, 258 depicted in FIG. 8A canbe the first primary link for a respective one robotic arm 202. In otherwords, as it relates to the embodiment of FIGS. 5A and 5B, thearrangement of FIG. 8A provides for three robotic arms 202. Regardless,the drive system 320 includes four barrel cams 322 arranged about acenter point 324 as shown in FIG. 8A so as to define a continuouscircle.

The track 204, including the inner and outer guides 220, 222 (shownschematically in FIG. 8A), is coaxially disposed above the barrel cams322. Each of the carts 206, 246, 258 are moveably mounted between theguides 220, 222 as previously described such that the track 204 guidesthe carts 206, 246, 258 through a curved path. Further, as best shown inFIG. 8B, each of the carts 206, 246, 258 includes a follower 326 sizedto ride within a track or path formed by, or cut into, the cams 322.Notably, each of the cams 322 can form a separate track for receivingand driving a respective one of the carts 206, 246, 258 via theassociated follower 326. That is to say, each of the carts 206, 246, 258can be connected to, and driven by, a single track formed in each of thecams 322 (via the respective followers 326). Alternatively, two or allof the carts 206, 246, 258 can be driven by separate tracks formed inthe cams 322.

During use, the four-barrel cams 322 are driven together, creating acontinuous inner cam surface akin to a rotating toroid. The followers326 are driven by the cams 322, and in turn drive the carts 206, 246,258 about the track 204. As such, the position, velocity, andacceleration of each of the carts 206, 246, 258, and thus of the roboticarm 202 associated with the respective carts 206, 246, 258, is commonlydictated by the drive system 320. By preferably forming each of thefour-barrel cams 322 with three tracks (correlating with the carts 206,246, 258, respectively), each of the robotic arms 202 (FIG. 5C) isprovided with three degrees of freedom driven by only three inputs. Withthis one particular embodiment, the track 204 is circular.

Yet another alternative embodiment decoupled continuous motion roboticdevice 350 is depicted in FIGS. 9A–9C. With specific reference to thetop view of FIG. 9A, the device 350 includes a plurality of robotic arms352 rotatable about a central hub 354 formed by a drive system 356 (onlya portion of which is illustrated in FIGS. 9A–9C). In particular, therobotic arms 352 are coaxially aligned relative to a centerline(referenced as “D” in FIG. 9A) of the central hub 354.

FIG. 9B illustrates construction of the robotic device 350 in greaterdetail. For ease of illustration, only one of the robotic arms 352 a isprovided in FIG. 9B, it being understood that each of the robotic arms352 are preferably identical in construction, and are stacked relativeto one another as described in greater detail below. With additionalreference to FIG. 9A, the robotic arm 352 includes a first input 358, asecond input 360, a third input 362 and an end effector 364. The firstinput 358 includes a first hub 366, a rigid, extension arm 368 and afirst coupler 370. The first coupler 370 is rotatably connected to thefirst extension arm 368 by a joint 372, and to the end effector 364 by ajoint 374. Similarly, the second input 360 includes a second hub 376, arigid, second extension arm 378 and a second coupler 380. The secondcoupler 380 is rotatably connected to the second extension arm 378 by ajoint 382, and to the end effector 364 by a joint 384. Finally, thethird input 362 includes a third hub 386, a rigid, third extension arm388 and a third coupler 390. The third coupler 390 is rotatablyconnected to the third extension arm 388 by a joint 392, and to the endeffector 364 by a joint 394.

Each of the hubs 366, 376, 386, and their respective extension arms 368,378, 388, serve as primary inputs or primary links for the robotic arm352 a, with the hubs 366, 376, 386 being rotatable about the centerpoint D (FIG. 9A). Further, by providing each of the inputs 358–362 withthe respective couplers 370, 380, 390, the inputs 358–362 serve askinematic dyads. The stacked arrangement of the inputs 358–362 providesthe end effector 364 with three degrees of freedom that are controlledby the relative positions of the three hubs 366, 376, 386, and inparticular the respective extension arms 368, 378, 388. In effect, then,any of the three hubs 366, 376, 386 can be designated as a “firstprimary link,” “second primary link,” or “third primary link,” as eachindependently dictates a position of the end effector 364. Along thesesame lines, any of the joints 392 along the axis D can be designated asa “first primary joint,” a “second primary joint,” or “third primaryjoint”.

Each of the other identically constructed robotic arms 352 (FIG. 9A) aresimilarly connected to inputs stacked above or below the inputs 358–362.With additional reference to FIG. 9C, for example, three robotic arms352 a–352 c are depicted. Each robotic arm 352 a–352 c is depictedgenerally as including the inputs 358–362, along with a respective endeffector 364. The inputs 358–362 can be rotated individually such thatany position of the respective end effectors 364 within its range ofmotion is available. For example, the end effector 364 can make aperfectly straight, flat motion to, for example, pick objects off of amoving belt, and then swing down and match an inverse arc to place theobject on a dial table. To offset potential cantilevering concerns,duplicate inputs 358 a′, 358 b′, 358 c′ are provided for the roboticarms 352 a–352 c to stiffen the respective end effectors 364.

In one preferred embodiment, each of the hubs 366, 376, 386 areindividual, hollow-shaft servo-motors, associated with the drive system356. The servo-motors can thus dictate a desired rotationalspeed/sequence for each of the inputs 358–362.

Alternatively, the drive system 356 associated with the device 350 canbe cam-based. More particularly, FIG. 10A provides a perspective view ofthe first hub 366, associated with the first input 358, configured as acylinder forming inner cam paths 400. Notably, the second and third hubs376, 386 are basically similarly constructed, although may form varyingcam paths to effectuate varying rotation of the various inputs 358–362.

With additional reference to FIG. 10B, one preferred cam-basedconfiguration of the device 350 includes a drive chain 402 having aplurality of links 404 each maintaining a follower 406. The followers406 are sized to be received within the cam paths 400 formed by the hubs366, 376, 386. Thus, linear movement of the drive chain 402 through abase tower 396 causes the followers 406 to engage the respective campaths 400, thereby rotating the respective inputs 358–362. With thisconfiguration, the spatial motion of the end effectors 364 (FIG. 9B) canbe “programmed” into the cam paths 400 formed by the hubs 366, 376, 386.As a point of reference, FIG. 10B illustrates only one of the roboticarms 352, it being understood that additional robotic arms 352 would besimilarly constructed and driven, essentially elongating the base tower396.

Regardless of the exact form, the continuous motion robotic device 20,50, 80, 150, 200, 240 or 350 not only facilitates processing of objectsthough a wide variety of different paths, but is also preferably highlyflexible and can be quickly modified to meet the needs of different workenvironments, performing a wide variety of object processing such aspick-and-place actions, applying coatings, assembling objects, variousother object manipulations, etc. For example, FIG. 11A illustrates afirst work environment 440 within which a continuous motion roboticdevice 442 (shown generally as including three decoupled robotic arms454) in accordance with the present invention is maintained. While thedevice 442 is illustrated as conforming with the “decoupled” robotic armconfiguration previously described, the “coupled” configuration is alsoapplicable. Regardless, the work environment 440 is shown as defining afirst station 444, a second station 446, and a third station 448. Itwill be understood that the work environment 440 illustrated in FIG. 11Ais but one example of a possible application of the robotic device 442.With this in mind, the first station 444 maintains a supply of objects450. The objects 450 are shown in block form, and can assume virtuallyany form. The second station 446 represents generally an applicatorstation at which a coating is applied to one of the objects 450.Finally, the third station 448 includes a conveyor 451 along which aseries of other objects 452 are conveyed. The operational sequenceincludes moving individual ones of the objects 450 from the firststation 444 to the second station 446 at which a coating is appliedthereto. The coated object 450 is then moved to the third station 448and placed onto one of the second objects 452. With these parameters inmind, a preferred rotational path (designated as “P1” in FIG. 11A) isdetermined for the robotic arms 454 as applied within the workenvironment 440. The drive system (not shown) associated with therobotic device 442 is then configured or programmed to drive the roboticarms 454 through the path P1. For example, the servo-motors or camsassociated with the drive system are correspondingly programmed orselected. Once properly configured, the robotic device 442 is installedwithin the work environment 440 and activated. The robotic device 442operates such that each of the three robotic arms 454 simultaneously andcontinuously process objects 450 through each of the three stations444–448.

From time-to-time, circumstance, such as a slight change in the objects450, may require a slight change in the path P1 within the workenvironment 440. For example, the objects 450 may vary in size frombatch to batch. This change in size may require a path P2 shown in FIG.11A. The robotic device 442 can be quickly modified to provide this pathby reprogramming servo-motor(s) associated with the drive system and/orchanging one or more cams. Alternatively, one or more feedback systems(e.g., position sensors, vision systems, etc.) may indicate thatsomething within the work environment 440 has changed (e.g., locationsof the objects 450 in the first section 444 deviating from an expectedposition). The robotic device 442 utilizes this feedback information,indicative of a change or revision in operational parameters, to quicklyachieve a revised or corrected path.

Similarly, the same robotic device 442 can easily be reconfigured forapplication in a second work environment 460 as shown in FIG. 11B. Inthis regard, the second work environment 460 is shown as generally asincluding first, second, third, and fourth stations 462–468. Once again,objects 470 must be processed through the stations 462–468. Based uponthe parameters/requirements of the stations 462–468, a rotational pathP3 for the arms 454 can be determined. While the path P3 associated withthe second work environment 460 is quite different from that of thefirst work environment (P1 in FIG. 11A), the robotic device 442 can beused within the second work environment 460 with minimal change. Inparticular, only the drive system (not shown) is altered. For example,where the robotic device 442 utilizes a servo-motor based drive system,one or more of the servo-motors are simply reprogrammed to achieve thearm path requirements of the second work environment 360. Alternatively,where the drive system is associated with the robotic device 342utilizes cams, one or more of the cams can be replaced with a differentcam specifically formatted to satisfy the path requirements of thesecond work environment 460.

The continuous motion robotic device of the present invention provides amarked improvement over previous designs. A plurality of robotic armsare coaxially arranged to continuously rotate about a common centralpoint. In one preferred embodiment, each of the arms is provided withthree degrees of freedom. Regardless of the number of degrees offreedom, each link associated with each arm is commonly driven by asingle input, such that the resulting device is highly flexible forvarying work environment requirements. In particular, by being highlyflexible and able to operate at high speeds, the continuous motionrobotic device of the present invention uniquely combines the advantagesof traditional dedicated machinery and robotic machinery.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present invention.

1. A continuous motion robotic device for processing objects, the devicecomprising: a first robotic arm; a second robotic arm; a third roboticarm; wherein the robotic arms are decoupled and each configured torotate a full 360° and each include an end effector for performing workon an object, and further wherein the robotic arms are arranged about acentral axis relative to one another, and further wherein at least aportion of two of the arms may pass through different angles, relativeto the central axis, at the same point in time; and a drive systemcommonly controlling the robotic arms, the drive system defining acentral axis about which the robotic arms rotate.
 2. The device of claim1, wherein the robotic arms are identical.
 3. The device of claim 1,wherein each of the robotic arms includes a first, second and thirdprimary link.
 4. The device of claim 1, wherein each of the robotic armsincludes a first primary link, a second primary link, a first primaryjoint connecting the first primary link to the drive system, and asecond primary joint connecting the first and second primary links. 5.The device of claim 4, wherein the second primary joints are rotaryjoints.
 6. The device of claim 4, wherein the first primary joints andthe second primary joints move independent of one another such that uponactivation of the drive system, the robotic arms are directed throughsubstantially identical paths and the end effectors are positioned at adifferent radial distance relative to the centerpoint during at leastone point in time.
 7. The device of claim 6, wherein the drive systemincludes: a closed loop track having an instant center at any point intime that defines the center point; and a plurality of first cartsseparately and moveably coupled to the track, respective ones of whichdefine respective ones of the first primary links, the instant centerpoint of the track defining the first primary joint.
 8. The device ofclaim 7, wherein each of the robotic arms further includes a thirdprimary link connected to the second primary link by a third primaryjoint.
 9. The device of claim 7, wherein the drive system furtherincludes a plurality of second joint servo-motors, respective ones ofwhich are connected to and drive respective ones of the second primaryjoints.
 10. The device of claim 9, wherein each of the robotic armsfurther includes a third primary link connected to the second primarylink by a third primary joint, and further wherein the drive systemfurther includes a plurality of third joint servo-motors, respectiveones of which are connected to and drive respective ones of the thirdprimary joints.
 11. The device of claim 7, wherein the track includes aninner guide member and an outer guide member, each of the carts beingmoveably mounted between the guide members.
 12. The device of claim 11,wherein the drive system further comprises: a stationary gear coaxiallydisposed below the track, the stationary gear having a toothed surfaceextending adjacent the inner guide member; and a plurality of drivegears, respective ones of which are secured to respective ones of theplurality of carts, the drive gears being configured to interface withthe stationary gear upon final assembly; wherein rotation of the drivegears causes the respective cart to articulate about the track via thestationary gear.
 13. The device of claim 1, wherein each of the threerobotic arms are co-planar.
 14. The device of claim 1, wherein theunrestricted motion is a dwell when the other arms are rotating.